RETRACTED: Adsorptive removal of cadmium (II) using P-oceanica biomass: effect of NaCl concentration on equilibrium and kinetic parameters (Retracted Article)

In this study, biosorption of cadmium (II) from saline solutions by Posidonia oceanica (L.), a marine biomass, was studied as a function of pH, initial cadmium (II) and NaCl concentrations in a batch system. The sorbent exhibited the maximal cadmium (II) uptake at pH 6 in the absence and in the presence of increasing concentration of NaCl. Equilibrium uptake increased with the cadmium (II) concentration up to 250mg/L and diminished considerably in the presence of increasing concentrations of salt up to 50g/L. At 100mg/L, initial cadmium (II) concentration, P. oceanica biosorbed 15.69mg/g of cadmium (II) without salt medium. When NaCl concentration was raised to 50g/L, this value dropped to 6.87mg/g of cadmium (II) at the same conditions resulting in 56.21% decrease in biosorption capacity. The equilibrium sorption data were analysed by using Freundlich, Langmuir and Redlich-peterson models. Langmuir was the most suitable adsorption model for describing the biosorption equilibrium data of cadmium (II) both individually and in salt-containing medium. Pseudo-second-order kinetic model also fitted well to both systems, viz. cadmium (II) and cadmium (II)+NaCl. Isotherm constants varied due to the level of salt were expressed as a function of initial NaCl concentration.